1. Field of the Invention
The present invention relates to an information display apparatus with a matrix of light-emitting diode picture elements (LED pixels).
2. Description of the Related Art
Vast numbers of information display devices with LED pixels are now in use, displaying public transportation destinations, for example. These devices comprise a large number of LED chips arranged in a matrix on an insulating substrate. The LED chips are switched on and off by a driving circuit disposed on the opposite side of the substrate to display text and graphics. The numerous LEDs in the matrix are individually die-bonded to the insulating substrate, then bonded by metal wires to electrodes on the surface of the insulating substrate, and finally covered with transparent plastic to provide a flat display surface.
A display device of this type is described in Japanese Patent Application Publication No. 2000-089694.
In these conventional information display devices, because the LED chips must be individually die-bonded and wire-bonded, a dense matrix of LEDs cannot be formed. The display therefore appears grainy, with strikingly poor image quality. A further drawback of these conventional LED matrices is that they are impractical for small information display devices, because they do not provide enough pixels to display useful text or graphics.